LEDs having an InGaN light emitting layer and a wavelength band of 375 nm-600 nm have been developed. In InxGa1-xN, the wavelength of emitted light varies when the proportion x of In is changed. More specifically, as the composition x of In is increased, the light emission wavelength is shifted toward a longer wavelength side, from 363 nm when x=0 (GaN) to 600 nm when x=1 (InN).
Recently, there have been active efforts to develop LEDs having a short wavelength of 375 nm or shorter or having an ultraviolet (UV) wavelength. Demand for such short wavelength LEDs is very strong as the short wavelength LEDs allow applications in, for example, a white light source in which the LED is combined with a fluorescent material or sterilization using the sterilizing characteristic of the LED. However, in an LED having an InGaN light emitting layer, in order to obtain a light emission wavelength of 375 nm or shorter, the composition x of In must be very small, resulting in a reduced fluctuation of In composition and, consequently, significant reduction in a light emission efficiency. In addition, fundamentally, when InGaN is used as the light emitting layer, light emission of wavelength of 363 nm or shorter cannot be achieved.